Heating unit



Nov. 21, 1939.

H. E, MILLS HEATING UNIT Filed June 42l, 1937 IJMIIM BY u Patented Nov. 21, 1939 Herbert E. Mills, Detroit, Mich., assignor to Borg- Warner Corporation, a corporation of Illinois Application vJune 21, 1937, SerialNo. 149,350

dClaims.

This invention relates to stoves in general and has particular reference to certain elements included in the heating element assembly adapted foruse in conjunction with an electric cooking range.

In any cooking compartment which is heated by electricity it is necessary to provide a heating resistance of some sort, a supporting means for the resistance, and insulating means for separating the former from the latter. The insulating means can take any particular form of construction, but it is best to provide an insulator which interferes as little as p'ossible with the heat emanating from theY heating element. The type of insulator disclosed herein is provided with an inner opening through which the heating element passes, and the wall of the opening nearest the heating element is formed in such a way as to provide the smallest area of contact between the v insulator and the element, namely, a line contact. lI'he insulator itself is supported at its periphery by the portions of the supporting member for the heating element directly adjacent thereto. The construction of the insulator and the elements used in the combination which includes the insulator is simple and, therefore, inexpensive, and it makes possible the loss of little or no heat from its use and also acts to maintain the natural direction of flow of the heat radiated from the element.

'I'he main object of the invention, therefore, is to provide in the combination of elements which is supported within a cooking compartment for furnishing the cooking heat thereto, an insulating member which is so constructed and so arranged that the loss ofheat or any change in the effectiveness thereof, due to the use of such member, is negligible.

- Another object is to provide in combination 4o with a supporting member for a heating element, a novel form of insulating member which is adapted for protecting the element from the supporting member and at the same time for causing little or no loss in heat from the element or little or nochange in the natural radiational paths of the heat therefrom.

Another object is to provide a novel form of insulator for use in connection with a heating element assembly for a cooking compartment,

which provides a minimum area of contact between it and the heating element with which it is associated.

Another object of the invention is to provide a compartment adapted for cooking therein with an improved form of heating element assembly,

' of high eillciency with low cost together with other appreciable advantages and novel features. Other objects of the invention will be apparent from a reference to the following specication taken in conjunctionl with `the accompanying 10 vdrawing of which there is one (1) sheet and in which: f

Fig. 1 is a vertical sectional view through a portion of a heating compartment in which the novel structure .comprising the invention is 15 .adapted to be disposed;

Fig. 2 is a plan view of a heating element and -`its supporting structure showing the invention -embodied therein and being partly broken away;

Fig. 3 is a cross sectional view through the 20 novel form of heat insulator used inthe structure vdisclosed in Fig. 2;

Fig. 4 is a cross sectional view taken along the plane indicated by the line 4 4 of Fig. 2 and showing in detail the vvarious elements compris- 25 ing the heating element assembly;

Fig. 5 is a cross sectional view taken along a plane as indicated by the line 5 5 of Fig. 2 and showing in detail the assembled relation between the insulator and its supporting means; and 30 Fig. 6 is a cross sectional View taken along a plane as indicated by the line 6 6 of Fig. 2 and showing the insulator and supporting means therefor in a view at right angles to that of Fig. 5.

Referring to Fig. 1, there is shown, generally 35 at I0, a portion of a heat insulated compartment having a movable closure member I2, a main rear wall I4, and a main top I6. Within compartment I0, and deiining one of its inner side walls, is a rack support I8 adapted for supporting a food 40 rack 20. Support I8 is held in place by a plurality of inserts 22 which are supported by and appropriately spaced on the walls of compartment III. Removably included in the upper por- 45 tion of the compartment back wall I4 is any well known form of female terminal block assembly, generally indicated at` 24, which is adapted for being electrically engaged by the male terminals of the heating element assembly to be 50 used for heating the space within compartment I0. Secured to the upper portion of each side wall of the compartment, and positioned for supporting the heating element assembly and guiding same for operative engagement with the fe- Y5i;

male block 24, is a channel iron 26 which extends from the i'ront to the rear oi the compartment.

In Fig. 2, there is shown a plan view of the heating element assembly, generally indicated at 28, which is adapted i'or use in compartment I@ and for being guided and supported by rails 26. The assembly 28 is comprised of an outer shell v which is formed by the union between iront and rear channel 'members 38 and 32 and side channel members 34 and 36. Members 38 and 32 have ends which terminate in anges extending at right angles to said members. These flanges are adapted to engage adjacent portions of members 34 and 36 and are secured thereto by means oi a plurality of nut and bolt arrangements, generally indicated at 36.A Forl strengthening this outer shell there is provided at each corner thereof (with the exception oi the corner adjacent the male terminal block) a gusset plate 46. One face of each of the plates 40 is welded or otherwise secured to its adjacent channel member 36 or 32, the other face having an opening therein for reception therethrough of one end of a supporting member 42. These supporting members 42 are threaded at each end and are adjustably secured to assembly 28 through channels 3d and 36, the iianges of channels 30 and 32, and plates 4u, each by means of a pair of double nut arrangements, generally indicated at 66. Members 42 constitute the portion of assembly 26 which is' engageable with and supported by the channeled rail members 26 disposed in compartment i6, and they therefore extend from the outer shell to such a distance as to permit assembly 28 to slide freely in and out of the compartment upon members 26 but, while in, to be iirmly supported by members 28.

The inner shell structure of assembly 28 is formed by a series of stampings 46 having ilanged end portions extending toward the front of the assembly 28 and seating snugly (but not secured thereto) in the channeled portions of members 34 and 36. Disposed on the flat side of each stamping 46, and secured thereto by pinching and lapping marginal portions of one over the other, is another stamping 48 having flanged ends which extend oppositely to the flanged ends of member 46 and are housed within the channeled portions of members 34 and 36, but are not secured thereto. For strengthening the inner shell of assembly 28 and also for partially supporting the heating element carried by the assembly is a plurality of assembled stampings 58 and 52 which are secured together in a manner similar to that used in joining stampings 46 and 46 together, and between thefront shell member 36 and its adjacent stamping unit 46-48, and/or between the rear shell member 32 and its adjacent stamping unit 46-48.l These stamping units 50-52 are secured to the outer shell by merely inserting Aportions of the ends of the unit 50-52 through apertures in the shell and then folding the ends against the shell thereby holding the shell and unit together, as designated at 54. 'I'here may also be provided a pair of assembled stamping units 56-58 for supporting the heating element at the corners thereof, and these units 56-58, if provided, are secured to the front member 30 similarly to the units 56-52.

It is to be expressly understood that the ar-I rangement of the inner shell structure is op tional, and that the one chosen for the sake of disclosure has proved most eiiicient for the length of heating element used. It is also to be understood that the construction is optional, and

that the construction chosen to be illustrated is inexpensive, practical, and able to contract and expand freely in accordance with the thermal conditions surrounding it.

Referring to Figs. 2 through 6, there is shown a heat insulator 66 having an outwardly extend-v ing marginal portion 62 and a central opening 64. The marginal portion 62 of insulator 66 is adapted to be iltted in an annular pocket formed between the members 46 and 46, members 66 and 62, and members 66 and 68. When so assembled, said members are then pinched closely together for providing means whereby the insulator 6l, by its marginal portion 62, is held in position with respect to said members. The central opening 64 in insulator 6U is formed by the intersection o! oppositely disposed frustums of cones disposed in each side of the insulator, thus providing the smallest area of opening 64 with a wall having the smallest possible width, namely, a line. This smallest area of opening 64 is made just slightly l larger than the diameter of the heating element adapted to be supported therein, the opening, after the assembly of insulator 66 in the aforementioned pocket, being lined up in accordance with openings provided therefor in the stamping members. f

Although insulator 66 is shown as being round, it may be any other shape, if so desired, and the area of the opening 66 may also be any shape other than round. The important thing is to provide an opening, the wall of which forms substantially no more than a line contact with the heating element passing therethrough.

For heating the compartment [D and supported by the assembly 26, is a heating element 66 each end of which is connected to a terminal 68, by means of a pair of holding means 16, oi' the male terminal block, generally indicated at 12, terminals 68 being electrically associated with the terminals 14 of block '12. Block '12 is secured to assembly 28 by means of nut and bolt arrangements, generally indicated at '16, and is so lo-l cated with respect to assembly 28 that, when the assembly 28 is inserted in compartment lli by engaging rod members 42 with guide rails 26, and then pushed rearwardly, the male terminals 14 will engage with the female terminals provided in the block 2.

'Ihe heating element 66, after leaving one of the terminals 68, winds in and out of the inner shell structure of assembly 28 by passing through the openings provided therefor in the insulators 60 and, after traversing enough area to provide the desired resistance for the necessary heating effect, returns to the other terminal 68 of the male block 12. In view of the novel construction of the insluator 66 which provides line contact between the insulator and the heating element and also the divergence of the sides of the opening 64 from the inner to the outer surfaces of the opening, the heating effect of the element is not materially diminished by the use of this type of insulator, It has been found that the use of this type of insulator has increased the efdciency of the heating element to such an extent that it is the equivalent of an ordinary heating element having twenty-five' or thirty inches more length. The insulator is adapted not only to provide a minimum, of interference with or diminution of the heat radiated from the element, but also to prevent any abnormal deflection of this radiated heat. And, the cost of manufacturing this type of insulator is necessarily lower than the cost of making the accepted insulator oi today.

While the invention has been described in some detail, it is to be understood that the description given is for the purpose of illustration only and is not to be construed as denitive of the limits of the inventive idea. The right is reserved to make such changes in the details of construction and arrangement of parts as will fall within the purview of the attached claims.

I claim:

1. In a device of the class described, a rectangular supporting frame Uz-shaped in cross section and open at the top and bottom, insulator supporting elements arranged transversely of the frame and having their end portions received and maintained but not attached within the U- shaped portion of the frame, other insulator sup.l porting members rigidly attached to said frame and the intermediate portion of said ilrst mentioned insulator supporting elements and spacing said rst mentioned insulator supporting elements from the ends of said frame, and an electrical resistor element threaded through the insulator supporting elements.

'2. In a device of the class described, a rectangular supporting frame having side portions formed of channel members, the legs of which converge toward one another, resistor supporting elements extending transversely of the frame and having their ends ared and loosely received .porting elements arranged transversely of the framework and having flared end portions loosely received within the converging legs of the U- shaped channels along the sides `of the framework, said supporting elements presenting a relatively negligible horizontal area and being arranged for longitudinal and limited transverse movement relative to said framework.

4. In a device of the class described, a rectangular frame member open at the top and bottom, resistor supporting members having a loose sliding connection with said frame meniber for support thereby, other resistor supporting elements having a xed connection to said frame and to the intermediate portions of said first mentioned resistor supporting members for spacing said rst mentioned resistor supporting members'relative to the ends of said frame.

HERBERT E. MILLS. 

